Anti-FCSK antibodies are used in the immunodetection of the protein fucose kinase. In humans, the canonical protein has a reported length of 1084 amino acid residues and a mass of 117.6 kDa. Up to 2 different isoforms have been reported for this protein. It is reported to be expressed in fibroblasts. It is a member of the GHMP kinase protein family. The FCSK gene has been associated with the disease, Congenital disorder of glycosylation with defective fucosylation. Synonyms for this target antigen include L-fucose kinase and fucokinase. FCSK gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.